/**
 * Screenshot helper for this env: geckodriver + headless Firefox.
 *   node dev/wd-shot.mjs <url> <setupExpr> <shotFile> [width] [height] [timeoutMs]
 * <setupExpr> is a WebDriver execute/sync script (function body) that runs on
 * the page before the screenshot; may be '' to skip. The page is given time
 * to finish loading (the expression is polled until it returns non-null).
 */
import { spawn, execFileSync } from 'node:child_process';
import { existsSync, readdirSync, writeFileSync } from 'node:fs';

const [url, setupExpr, shotFile, w = '1280', h = '720', timeoutMs = '30000'] = process.argv.slice(2);
const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

let geckodriver;
try { geckodriver = execFileSync('sh', ['-c', 'command -v geckodriver'], { encoding: 'utf8' }).trim(); }
catch { console.error('need geckodriver on PATH'); process.exit(2); }

const firefoxCandidates = [];
try {
  const ff = execFileSync('sh', ['-c', 'command -v firefox'], { encoding: 'utf8' }).trim();
  if (ff) firefoxCandidates.push(ff);
} catch { /* ignore */ }
try {
  const snapRev = readdirSync('/snap/firefox', { withFileTypes: true }).map((d) => d.name);
  for (const rev of [null, ...snapRev]) {
    const base = rev ? `/snap/firefox/${rev}` : '/snap/firefox/current';
    const p = `${base}/usr/lib/firefox/firefox`;
    if (existsSync(p)) firefoxCandidates.push(p);
  }
} catch { /* no snap firefox */ }
if (firefoxCandidates.length === 0) { console.error('no firefox binary'); process.exit(2); }

const PORT = 4460 + (process.pid % 50);
const driver = spawn(geckodriver, ['--port', String(PORT), '--log', 'fatal'], { stdio: 'ignore' });
const base = `http://127.0.0.1:${PORT}`;
const fail = (msg, code = 1) => { try { driver.kill('SIGKILL'); } catch { /* ok */ } console.error(msg); process.exit(code); };

const wd = async (method, path, body) => {
  const res = await fetch(base + path, { method, headers: { 'Content-Type': 'application/json' }, body: body === undefined ? undefined : JSON.stringify(body) });
  const text = await res.text();
  let data = null; try { data = JSON.parse(text); } catch { /* ignore */ }
  if (!res.ok) throw new Error(`WebDriver ${method} ${path} → ${res.status}: ${text.slice(0, 300)}`);
  return data;
};

try {
  let up = false;
  for (let i = 0; i < 60; i++) {
    try { const v = await (await fetch(`${base}/status`)).json(); if (v?.value?.ready || v?.status === 'ok' || v?.value) { up = true; break; } } catch { /* not up */ }
    await sleep(250);
  }
  if (!up) fail('geckodriver never came up');

  let sess; let lastErr = null;
  for (const ff of firefoxCandidates) {
    try {
      sess = await wd('POST', '/session', {
        capabilities: { alwaysMatch: {
          browserName: 'firefox',
          'moz:firefoxOptions': { args: ['-headless'], binary: ff },
        } },
      });
      break;
    } catch (err) { lastErr = String(err?.message ?? err); }
  }
  if (!sess) fail(`no firefox candidate accepted: ${lastErr}`);
  const sid = sess.value?.sessionId;
  if (!sid) fail('no session id');

  if (w && h) {
    try { await wd('POST', `/session/${sid}/window`, { handle: 'current', state: { width: Number(w), height: Number(h) } }); } catch { /* keep default size */ }
  }
  await wd('POST', `/session/${sid}/url`, { url });

  if (setupExpr) {
    const deadline = Date.now() + Number(timeoutMs);
    let last = null;
    while (Date.now() < deadline) {
      await sleep(250);
      try {
        const r = await wd('POST', `/session/${sid}/execute/sync`, { script: setupExpr, args: [] });
        if (r.value !== undefined && r.value !== null) { last = r.value; break; }
      } catch (err) { last = `ERR ${String(err?.message ?? err)}`; }
    }
    if (last === null) fail('setup expression never returned a value');
    if (typeof last === 'string' && last.startsWith('ERR')) fail(last);
    console.log('setup →', JSON.stringify(last).slice(0, 400));
    await sleep(400);
  }

  const shot = await wd('GET', `/session/${sid}/screenshot`);
  writeFileSync(shotFile, Buffer.from(shot.value, 'base64'));
  console.log('saved', shotFile);

  await wd('DELETE', `/session/${sid}`).catch(() => {});
} finally {
  try { driver.kill('SIGKILL'); } catch { /* ok */ }
}